2021ApJ...914...36I

We present Atacama Large Millimeter/submillimeter Array [C II] 158 µm line and underlying far-infrared (FIR) continuum emission observations (0.''70 x 0.''56 resolution) toward HSC J124353.93+010038.5 (J1243+0100) at z = 7.07, the only low-luminosity (M₁₄₅₀ > -25 mag) quasar currently known at z > 7. The FIR continuum is bright (1.52 mJy) and resolved with a total luminosity of L_FIR = 3.5 x 10¹² L_☉. The spatially extended component is responsible for ∼40% of the emission. The area-integrated [C II] spectrum shows a broad wing (FWHM = 997 km s^–1, L_[C II]_ = 1.2 x 10⁹ L_☉), as well as a bright core (FWHM = 235 km s^–1, L_[C II]_ = 1.9 x 10⁹ L_☉). This wing is the first detection of a galactic-scale quasar-driven outflow (atomic outflow rate >447 M_☉ yr^–1) at z > 7. The estimated large mass-loading factor of the total outflow (e.g., >=9 relative to the [C II]-based star formation rate) suggests that this outflow will soon quench the star formation of the host. The core gas dynamics are governed by rotation, with a rotation curve suggestive of a compact bulge (∼3.3 x 10¹⁰ M_☉), although it is not yet spatially resolved. Finally, we found that J1243+0100 has a black hole mass-to-dynamical mass (and -to-bulge mass) ratio of ∼0.4% (∼1%), consistent with the local value within the uncertainties. Our results therefore suggest that the black hole-host coevolution relation is already in place at z ∼ 7 for this object.